Growing transistor densities and an ever-increasing demand for digital data have contributed to a general increase in the power consumed by integrated circuits and integrated circuit packages. This trend toward increased power consumption can be costly in terms of both the actual price of electricity expended by the integrated circuits and the price associated with cooling the integrated circuits as heat is generated by operation of the integrated circuits and must be dissipated. Because of this general rise in the power consumption of integrated circuits, research is being performed into improved power management for such integrated circuits, particularly complex integrated circuitry such as processor cores.
Power consumption in integrated circuits can generally be classified into a dynamic component and a static component. Dynamic power consumption refers to the amount of power consumed by an integrated circuit that is dependent on the level of activity of the logic transistors in the circuit. Dynamic power consumption is sometimes managed by regulating the amount of voltage provided to active transistors and/or the frequency with which the transistors are switched during logic operations. Static power consumption refers to the component of power consumption resulting from leakage current conducted by transistors regardless of the activity status of the transistors. Static power consumption can generally be reduced only by cutting off power to the integrated circuit.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.